Field of the Invention
The present invention relates to a technique of controlling a backlight to be used in a displaying apparatus displaying image data.
Description of the Related Art
Conventionally, when original image data and intermediate image data are alternately displayed at same luminance on a liquid crystal displaying apparatus, a portion in which the intermediate image data has been disturbed stands out because the intermediate image data is not data which has been created completely. To cope with such inconvenience, Japanese Patent Application Laid-Open No. 2008-070838 discloses the technique in which light for original image data is emitted brightly and light for intermediate image data is emitted darkly, whereby a portion in which the intermediate image data has been disturbed does not so stand out. Besides, Japanese Patent Application Laid-Open No. 2008-0083457 discloses the technique in which light emission is performed so as to display original image data long time and display intermediate image data short time.
In addition, as one of conventional displaying methods, there is a method of holding a display while continuously causing a backlight to emit light. However, when holding the display, a moving image is viewed blurrily. Consequently, an apparatus such as a television set or the like of displaying moving images includes a type of controlling light emission of a backlight. For example, a technique which is called black insertion has been generally known. In this technique, if it intends to sharpen the moving image by prolonging a black insertion time, there is a problem that a flicker occurs when the moving image is displayed based on short light emission at 60 Hz. Therefore, when displaying the moving image by performing the light emission twice for a short time in one frame to prevent the occurrence of the flicker, there is a problem that the moving image is viewed doubly.
On the other hand, Japanese Patent Application Laid-Open No. 2002-215111 discloses the technique of controlling to prolong a light emission time of a backlight in conformity with necessary luminance. Further, Japanese Patent Application Laid-Open No. 2009-251069 discloses the technique of controlling to prolong a light emission time of a backlight in a period portion which is close to the center, in conformity with necessary luminance.
However, in addition to the problem of the disturbance of the intermediate image data, there is the problem of the occurrence of the flicker. As in the above related art, since the flicker occurs when the image is displayed in two kinds of states, i.e., brightly and darkly, the flicker becomes strong when a contrast between light and darkness is made large, whereby it becomes difficult for a viewer to easily view the displayed image. For this reason, there is a limit in enlarging the contrast between light and darkness. Moreover, a phenomenon in which the surrounding area of a displayed object visually flickers occurs due to a difference between the waveforms of the original image data and the intermediate image data. Furthermore, when emitting light for a long time to brighten the intermediate image data, there is another problem. That is, in the displayed portion which is moving, even though the intermediate image data is generated, the generated image is viewed like an image which trails. Such a phenomenon in which the image trails is called moving image blurring.
In consideration of such conventional drawbacks as described above, an object of the present invention is to perform a high-quality image display.